The present invention relates to a heat pump water heater with an internal condenser, a thermosiphon tube, and a pump.
Tank-type heat pump water heaters (HPWH) with internal condensers are known. In such known HPWH's, the condenser extends through the top of the water tank into the water tank to a coiled section within a bottom portion of the water tank. The condenser then extends back through the top of the water tank. In such internal coiled condenser designs, the condenser extends vertically through the water tank to the coiled section. The condenser transfers heat from refrigerant passing through the condenser as part of a refrigeration cycle. Due to the condenser being located inside the water tank, the storage volume of the water tank is reduced. Due to low water side heat transfer, typically the condenser needs to be very long to achieve higher efficiency, further reducing the storage volume. Longer condensers also require a larger refrigerant charge to operate. Therefore, it is beneficial to have a shorter condenser tube. However, shorter condenser tubes also have reduced heat transfer efficiency. As such, there is a desire to create a heat pump water heater that both has a condenser short in length and has high heat transfer efficiency.